Mercurial is a distributed version control system which features:

o Extremely high-performance delta-compressed storage scheme.
o Optimized for disk layout and access efficiency.
o Complete cross-indexing of files and changesets.
o Bandwidth and CPU efficient HTTP and SSH sync protocols.
o Distributed development model supports unlimited numbers of
  developers.
o Allows arbitrary merging between developer branches.
o Doesn't significantly degrade with large numbers of files or
  changesets.
o No waiting for locks!
o SHA1 integrity checking on repository data.
o Append-only storage model with transaction journalling.
o Fast full-repository verification.
